Last January I wondered if psychopaths dream — and noted that the only mammal (or maybe one of the few mammals) that doesn’t dream is a platypus. This post follows up, with a discussion of the “Platypus Defense” as part of the murder trial of Hans Reiser. Plus platypus genome and microRNA and transposable elements research.

During last January’s White Matter Days I pondered whether psychopaths have white matter defects which, in essence, unplug the empathy part of the brain from the cognitive part of the brain. This was from my own observations that the psychopaths (my unprofessional assessment) and alcoholics I know don’t report dreams. The only other mammal which probably doesn’t dream is a platypus– :

. . .So far, REM sleep originates in the brain stem, and dreams have something to do with the frontal lobes. White matter lesions — like those caused by addiction to alcohol or substance abuse — cause reduction in dreams, and lesions in the ventromedial prefrontal white matter cause cessation of dreaming. Dream imagery has something to do with complex cognitive processes bounced around between frontal areas of the brain.

One interesting thing is that mammalian babies also have REM sleep but no electrical activity in the frontal lobes, until they have further neurological development when they’re older. So perhaps psychopaths — and I would suspect people with fetal alcohol effects or perhaps in utero exposure to other toxic conditions — have essentially under developed neurological systems, similar to that of a mammalian baby — or, apparently, a platypus. Alcoholism also can work in reverse — to eliminate dreaming (there is a 1980 paper on this reproduced, scroll to the end of my previous post).
Dr. Franklin, of “In the News” (newly added to refreshed blogroll, at left) has a report on the Reiser murder trial , from last April, entitled,”The Platypus Defense”. Reiser –who was found guilty of first degree murder of his ex-wife — had explained away things like his dis-assembled car (having his ex-wife’s blood in it), and other fairly damning circumstantial evidence by saying, basically, “Hey, I’m an odd, computer-programmer, guy. . ” I think the defense-shrinks testified that he had Asperger’s or Narcissistic Personality Disorder — neither of which rises to a mitigating factor in murdering someone having malice aforethought.

His defense attorney — dealt a bum hand by this client, no doubt, who insisted on controlling his legal defense and testifying — created the “hey, platypus are odd, but they’re not murderers” type of argument (as live-blogged here
by the SF Chronicle reporter Henry K. Lee, scroll down to April 17):

. . .All this time, the picture of the platypus has been projected on the screen. “Did you know that the platypus is the only mammal that lays eggs?” Du Bois [defense counsel] asked, smiling. “I was trying to think recently how a platypus could even evolve. It must have been a genetic mistake. That’s why it reminded me of…” Du Bois trailed off but turned his head and gave a disdainful look at his client. Some laughter in the courtroom.

* * *

Speaking of platypuses (platypi!?), Du Bois said at one point, “I just know this is one of the great screw-jobs of what happened to Hans Reiser. It’s easy to screw a platypus.” He also remarked, “I don’t know how they stay away from predators. They must taste terrible.”

But the prosecutor would have none of it (emphasis added):

Hora [the prosecutor] said the platypus is actually one of the few venomous mammals in existence. He put up a slide that said as much and noted that the male platypus has a spur on the hind foot that delivers a venom capable of causing severe pain to humans. Many jurors smiled or laughed in amusement.

Hora referred to this “platypus nonsense” and other defense arguments as “nonsense, lies and his baloney.” “It doesn’t cut it,” Hora said. “And his excuses about all the things that he did. Odd by itself just doesn’t cut it.”

And Dr. Franklin’s entry adds a recording! of a vicious platypus. So I’d say that the platypus defense, like the platypus itself in evolutionary terms, is an adventitious vestige of the evolution of US jurisprudence.

One more platypus item of note: genomic information. Warren et al. report on Platypus genomic analysis and Murchenson et al. report on small RNA. One thing which jumped out at me from these two reports is the imprortance of extra-genomic elements which move around to either encourage genetic alteration or prevent it. Platypus seem to have an extra dose of these little bitty genetic jumping beans, which is interesting to contemplate that these have been instrumental in holding the platypus hostage to that no-mans land between reptile, bird and mammal.

That closes the book on platypus as far as I’m concerned; they are now a matter of supreme indifference to me.

We present a draft genome sequence of the platypus, Ornithorhynchus anatinus. This monotreme exhibits a fascinating combination of reptilian and mammalian characters. For example, platypuses have a coat of fur adapted to an aquatic lifestyle; platypus females lactate, yet lay eggs; and males are equipped with
venom similar to that of reptiles. Analysis of the first monotreme genome aligned these features with genetic innovations. We find that reptile and platypus venom proteins have been co-opted independently from the same gene families; milk protein genes are conserved despite platypuses laying eggs; and immune gene
family expansions are directly related to platypus biology. Expansions of protein, non-protein-coding RNA and microRNA families, as well as repeat elements, are identified. Sequencing of this genome now provides a valuable resource for deep mammalian comparative analyses, as well as for monotreme biology and conservation.

Small RNA pathways play evolutionarily conserved roles in gene regulation and defense from parasitic nucleic acids. The character and expression patterns of small RNAs show conservation throughout animal lineages, but specific animal clades also show variations on these recurring themes, including species-specific small RNAs. The monotremes, with only platypus and four species of echidna as extant members, represent the basal branch of the mammalian lineage. Here, we examine the small RNA pathways of monotremes by deep sequencing of six platypus and echidna tissues. We find that highly conserved microRNA species display their signature tissue-specific expression patterns. In addition, we find a large rapidly evolving cluster of microRNAs on platypus chromosome X1, which is unique to monotremes. Platypus and echidna testes contain a robust Piwi-interacting (piRNA) system, which appears to be participating in ongoing transposon defense.